(a) Technical Field
The present invention relates to a polyketone composition with improved impact resistance.
(b) Background Art
Polyketone (PK) is a terpolymer derived from polymerization of monomers of carbon monoxide, ethylene, and propylene. The price of these raw materials is rather inexpensive and the cost for its polymerization process is relatively low, compared to other engineering plastics such as polyamide, polyester, polycarbonate or the like. Polyketone also has excellent heat resistance, chemical resistance, fuel permeation resistance, and abrasion resistance. Thus, due to its impact resistance, it may be applied to various industrial fields.
Polyketone may be blended with polyamide 6 (PA6) to improve its impact resistance, but the impact resistance is less effective when it is in a dry state as described in Korean Patent No. 10-2010-0065526. In contrast, in a moist state, it markedly enhances the impact resistance properties which are described in the Journal of Applied Polymer Science, Vol. 116 (2010), pp 3056-3069. It may, however, result in a decrease in impact resistance at sub-zero temperatures and dimensional instability of parts.
A core-shell type rubber (e.g., a polybutadiene core with a styrene-acrylonitrile shell) may be introduced into polyketone to improve its impact resistance. However, in order to achieve a considerable improvement in impact strength, the rubber content should be about 20 wt % or more in the case of temperatures of −30° C. or lower, which markedly reduce flexural modulus, leading to reduction in the product hardness.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.